There are two types of working dogs for civilians. They are designed to help a person in everyday life. In public places, doors are open everywhere for them, and employees of restaurant stores are trained in special behavior with tailed ones.
The most common are the Emotional Support Animal (ESA) — in fact, it can be almost any animal, but more often they are dogs or cats. The ESA provides emotional support to its owner and helps him stabilize his mood (mental health). These dogs do not require special training.
ESA animals are eligible to accompany their owner on flights and do not have to pay for them in a rented apartment (because it is in service). The animal becomes an emotional support after the owner receives a written recommendation from their therapist or psychiatrist. Most often, such a recommendation is given to war veterans and victims of psychological and/or physical abuse. In addition, emotional support animal owners are not restricted by age, marital status, or immigration status in the country. But a prerequisite, which is valid from January 1, 2019: the ESA animal must be older than 4 months. This is done for the safety of the caudate, because at this age all vaccinations have not yet been made and, accordingly, it is too early to travel. Service dog (service dog), as is clear from the definition, can only be dogs. Quite stringent requirements are set for them, but they also have more “goodies”.
Official sources say that Labradors or Border Collies can be service dogs. Given the local characteristics of mixing breeds, the fulfillment of these requirements is blurred. You can often meet both German Shepherds and Maltese lapdogs. The next and most important requirement is that the dog must pass aptitude and training tests. The training lasts 120 hours (more than 6 months) and 30 of them in public places. During the training, the dog goes through 24 "topics", on which there will be an exam at the end. Also, at the end of the entire training, the dog must pass an exam of five tasks: not to show aggression to the stimulus; "go to the toilet" on command; do not be distracted by smells (in fact, the dog should not sniff); do not require food and attention; do not be playful (show activity only on command).
One person can have only one emotional support animal or one service dog, and never one or two at a time. All animals are required to wear identification vests (helmets) in public places. In fact, I rarely see them.
If this area interests you, you should read about National Service Animal Registrar and it will be useful for you